CVE-2026-84311

MEDIUMPre-NVD 4.84.8—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 96% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
4.8EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

pypdf is a free and open-source pure-python PDF library. Prior to 6.16.1, an attacker can craft a PDF that causes pypdf/_page.py PageObject._extract_text and PageObject.extract_xform_text to traverse a directed acyclic graph of reused form XObjects in which each form invokes a child multiple times, creating exponentially many traversal paths and causing long runtimes and large memory consumption. This issue is fixed in version 6.16.1.

CVSS v3
4.8
EG Score
4.8(medium)
EG Risk
22(Track)
EG Risk 22/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity48% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
4%
KEV
Not listed

Published

September 1, 2026

Last Modified

September 9, 2026

Advisory Details (4)

Auto-updated Sep 1, 2026
Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available

Version 6.16.1, 2026-08-14

Patch available: py-pdf/pypdf 6.16.1

https://github.com/py-pdf/pypdf/releases/tag/6.16.1
github_commit Patch Available

commit d91ab705fd81 (py-pdf/pypdf)

Patch available: py-pdf/pypdf 6.16.1 (contains commit d91ab705fd81)

https://github.com/py-pdf/pypdf/commit/d91ab705fd81ed1a9cec175c6958600dea1a4942
github_pr Patch Available

SEC: Limit iterations for outline retrieval and XForm text extraction

Patch available: py-pdf/pypdf 6.16.1 (PR #3966 merged 2026-08-14)

https://github.com/py-pdf/pypdf/pull/3966
github Patch Available

Possible long runtimes/large memory usage when extracting XForm objects · Advisory · py-pdf/pypdf · GitHub

https://github.com/py-pdf/pypdf/security/advisories/GHSA-763m-79hh-57f2

Vendor Advisories for CVE-2026-84311(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(5 across 4 ecosystems)
Debian:12(2)
PackageVulnerable rangeFixed inDependents
pypdf3.17.4-1 ... 6.9.2-2 (14 versions)——
pypdf22.12.1-3, 2.12.1-3+deb12u1, 2.12.1-4——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
pypdf5.4.0-1, 6.9.0-1, 6.9.2-1, 6.9.2-2——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
pypdf5.4.0-1, 6.9.0-1, 6.9.2-1, 6.9.2-2——
PyPI(1)
PackageVulnerable rangeFixed inDependents
pypdf1.0 ... 6.9.2 (114 versions)6.16.1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 30× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 10:10 UTCEG score recompute
  3. 2026-09-17 19:32 UTCEPSS rescore
  4. 2026-09-17 10:56 UTCEG score recompute
  5. 2026-09-16 14:09 UTCEPSS rescore
  6. 2026-09-16 11:42 UTCEG score recompute
  7. 2026-09-16 05:15 UTCEPSS rescore
  8. 2026-09-15 12:28 UTCEG score recompute
  9. 2026-09-15 03:12 UTCEPSS rescore
  10. 2026-09-15 03:12 UTCEPSS rescore
  11. 2026-09-14 13:13 UTCEG score recompute
  12. 2026-09-13 13:59 UTCEG score recompute
  13. 2026-09-11 15:31 UTCEG score recompute
  14. 2026-09-11 14:53 UTCEPSS rescore
  15. 2026-09-11 14:53 UTCEPSS rescore
  16. 2026-09-10 16:16 UTCEG score recompute
  17. 2026-09-08 23:20 UTCEG score recompute
  18. 2026-09-08 22:01 UTCEPSS rescore
  19. 2026-09-07 14:54 UTCEG score recompute
  20. 2026-09-06 13:48 UTCEPSS rescore
  21. 2026-09-06 13:37 UTCEG score recompute
  22. 2026-09-05 15:31 UTCEPSS rescore
  23. 2026-09-04 15:10 UTCEG score recompute
  24. 2026-09-04 05:07 UTCEPSS rescore
  25. 2026-09-03 15:55 UTCEG score recompute
Show 5 more
  1. 2026-09-02 16:20 UTCEG score recompute
  2. 2026-09-02 14:12 UTCEPSS rescore
  3. 2026-09-01 21:27 UTCEG score recompute
  4. 2026-09-01 20:24 UTCEG score recompute
  5. 2026-09-01 20:22 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-84311?
CVE-2026-84311 is a medium vulnerability published on September 1, 2026. pypdf is a free and open-source pure-python PDF library. Prior to 6.16.1, an attacker can craft a PDF that causes pypdf/page.py PageObject.extracttext and PageObject.extractxform_text to traverse a directed acyclic graph of reused form XObjects in which each form invokes a child multiple times,…
When was CVE-2026-84311 disclosed?
CVE-2026-84311 was first published in the National Vulnerability Database on September 1, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-84311 actively exploited?
CVE-2026-84311 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 96.4% of all scored CVEs.
What is the CVSS score of CVE-2026-84311?
CVE-2026-84311 has a CVSS v3 base score of 4.8 (NVD).
How do I remediate CVE-2026-84311?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-84311, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-84311

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